1. Field of the Invention
The present invention provides compounds comprising a lactam moiety and a urethane or urea functional group. By a prefer synthesis route, they are prepared using a compound comprising a polymerizable moiety and an isocyanate moiety, and reacting it with a hydroxyalkyl lactam or an aminoalkyl lactam. Such compounds may be converted to a wide variety of homopolymers and non-homopolymers.
Alternatively, compounds of the invention may be prepared by reacting a preformed polymer comprising an isocyanate moiety with a compound comprising a hydroxyalkyl lactam moiety or at least one aminoalkyl lactam moiety.
The compounds of the invention may find useful service in any number of arts, including (but not limited to): adhesive, agricultural, biocides, cleaning, coating, electronics, encapsulation, membrane, microelectronics, oilfield, performance chemical, personal care, sealant, and sensor applications.
2. Description of Related Art
N-vinyl lactam-based polymers are those polymers having a lactam group, such as pyrrolidone or caprolactam, where the lactam nitrogen is directly bonded to the polymer backbone. These polymers, which include poly(N-vinyl-2-pyrrolidone), poly(N-vinyl-ε-caprolactam), and poly(N-vinyl-2-pyrrolidone-co-N-vinyl acetate), are available in a wide range of molecular weight, which allows them to find use in many application arts, e.g., as film formers, protective colloids, and suspending agents, among many other uses. A description of these applications and properties is provided in the technical brochure “PVP Polyvinylpyrrolidone Polymers,” published by International Specialty Products, which is incorporated in its entirety by reference.
The success of N-vinyl lactam polymers is attributed in part to the chemical structure of the lactam group. With its lone pair of electrons, the lactam nitrogen can form hydrogen bonds with compounds containing —OH and —NH groups. Such interactions can be manifested in a variety of properties, including adhesion (e.g., glue sticks, hair styling, tablet binder), crystallization inhibitor (e.g., gas hydrates, sucrose solutions), and complexation agent (e.g., dyes, active ingredients).
In addition to the molecular weight, the number of carbon atoms in the lactam ring can be varied. Commonly known lactams include those from three carbon atoms/one nitrogen atom in the ring (propiolactam) up to six carbon atoms/one nitrogen atom in the ring (heptanolactam). Increasing the number of carbon atoms in the ring alters the molecule's water hydrophilicity/hydrophobicity balance. Although both poly(N-vinyl-2-pyrrolidone) and poly(N-vinyl-ε-caprolactam) are water soluble, the former is more hydrophilic, absorbing more water in humid environments than the latter.
However, the available ranges in lactam ring size and polymer molecular weight are insufficient to design new monomers and polymers with truly new functionality. For example, because the nitrogen atom of N-vinyl lactams is directly attached to the polymer backbone without a spacer group, there are limited options to modulate the hydrophilicity/hydrophobicity balance of the molecule, or to alter a relatively high glass transition temperature [e.g., about 180° C. for poly(N-vinyl-2-pyrrolidone)]. A new approach is needed that alters the structure of the N-vinyl lactam structure to facilitate new properties and end applications.
To attain different properties current technology relies on copolymerizing other monomer units together with the N-vinyl lactam unit. Many such non-homopolymers are known, and include those formed with N-vinyl acetate, styrene, dimethylaminoethylmethacrylate, dimethylaminopropylmethacrylamide, acrylic acid, and lauryl methacrylate. A number of properties can be altered through these copolymerizations, including hydrophobicity/hydrophilicity, film formation, flexibility, foaming ability, humidity response, viscosity, gloss, and tack. While copolymerizations produce valuable products, they are, in essence, pursued when the homopolymer cannot provide the desired properties. Desired are new lactam-based monomers and polymers thereof that offer expanded functionality.
In addition to functionality limitations, N-vinyl lactam based polymers require production methods and analytical testing to ensure sufficiently low residual monomer. Needed are next-generation lactam-based compounds that provide new properties and also are free of N-vinyl lactam monomer.
There is a related family of compounds, also based on N-alkyl lactams that help extend lactam moiety, in which an alkyl group is covalently bonded to the lactam nitrogen. Various N-alkyl lactams are known, and include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-octyl-2-pyrrolidone, and N-dodecyl-2-pyrrolidone, all of which are offered for commercial sale by International Specialty Products (Wayne, N.J.). Also known is N-hydroxymethyl-2-caprolactam (Benson, 1948). These non-polymeric chemicals find application as solvents, surface tension reducers, and low-foaming surface wetting agents.
The prior art teaches several modified N-vinyl lactams via N-alkyl lactams. These documents include: U.S. Pat. Nos. 2,882,262; 4,008,247; 4,189,601; 4,190,582; 4,191,833; 4,191,834; 4,439,616; 4,609,706; 5,209,347; 5,252,689; 5,466,770; 6,369,163; 6,630,599; and US patent applications: 2007/123,673; and foreign patents: EP385,918; EP550,744; and foreign patent applications: WO91/12243; WO02/42383; WO03/006568; WO2007/051738; WO 2008/098885, WO 2008/098887. Many of these publications describe various esters of N-hydroxyalkyllactams, such as N-hydroxyethylpyrrolidone. However, the compositions disclosed in the present invention have not been taught.
Also related is U.S. Pat. No. 6,630,599, which describes hydroxy-, amino-, lactam-, or cyclic urea-blocked derivatives of m- or p-isopropenyl-α,α-dimethylbenzyl isocyanates. These blocked derivatives of isopropenyl-α,α-dimethylbenzyl isocyanate include compounds of the general structure:
wherein G is:
wherein R1 or R2 is, individually, H or a C1-C4 alkyl, n is an integer of from 2 to 4, inclusive, q is 1 or 2, and R3 is a C1-C4 alkyl.